Turkey has called on the US-led coalition against Islamic State to provide air support to troops battling rebels in the key town al Bab.

The Russian air force carried out airstrikes on Sunday and Turkey said 226 militants had been "neutralised" in its latest operation but troops had been unable to take complete control of the Syrian town.

Turkish President Tayyip Erdogan's spokesman, Ibrahim Kalin, said: "The international coalition must carry out its duties regarding aerial support to the battle we are fighting in al Bab.

"Not giving the necessary support is unacceptable."

Rebels supported by Turkish troops have laid siege to the town for weeks in the "Euphrates Shield" operation launched by Turkey nearly four months ago to sweep the Sunni hardliners and Kurdish fighters from its Syrian border.

Mr Erdogan's spokesman said intense international efforts were being made to bring a ceasefire across Syria.

He also said more than 44,000 people had now been evacuated from Aleppo.

Video:President Assad makes Christmas visit to orphanage

Meanwhile, a video showing Bashar al Assad visiting a Christian orphanage near the capital Damascus on Christmas Day has emerged.

Photographs posted on the Syrian President's Facebook page showed him with his wife, Asma, standing with nuns and orphans in the Damascus suburb of Sednaya.

In the northern city of Aleppo, Christians celebrated Christmas for the first time in four years with the country's largest city after it came under full control of government forces.

Video:Nightmare vision: Video shows the destruction of Aleppo

The rebel withdrawal from east Aleppo last week marked Mr Assad's biggest victory since Syria's crisis began in 2011.

Christians, one of the largest religious minorities at about 10% of Syria's pre-war 23 million-strong population, have tried to stay on the sidelines of the conflict.